M&M Chocolate Chip Bars

These M&M Chocolate Chip Bars are a joyful, colorful twist on a classic cookie bar. They bake up with a buttery, tender crumb studded with mini or regular M&Ms and melty semi-sweet chocolate chips. Expect a soft, slightly chewy interior with lightly browned edges and pops of chocolate and candy in every bite. The aroma while baking is warm and nostalgic, a blend of brown sugar, vanilla, and melted chocolate that fills the kitchen and invites company. These bars are ideal for bake sales, school lunches, potlucks, or anytime you want an easy dessert that feeds a crowd. If you love the comforting feel of a classic chocolate chip cookie, you will appreciate how these bars concentrate that same flavor into a sliceable pan treat, similar in spirit to other family favorites like a classic chocolate chip cookie or a giant chocolate chip cookie for sharing.

Ingredients

2 and 3/4 cups all-purpose flour, measured spooned and leveled for accurate structure and tenderness.
1 and 1/2 teaspoons cornstarch, adds a soft, delicate crumb.
1 teaspoon baking soda, the leavening agent to give slight lift and lightness.
1/2 teaspoon salt, balances sweetness and enhances flavor.
1 cup unsalted butter, melted and cooled, provides rich flavor and a tender texture.
1 cup packed light or dark brown sugar, adds moisture and a deep caramel note.
1/2 cup granulated sugar, for sweetness and slight crisping at the edges.
2 large eggs, at room temperature, for structure and richness.
2 teaspoons pure vanilla extract, boosts overall flavor and aroma.
1 and 1/4 cups mini or regular-size M&Ms, for colorful candy crunch throughout.
3/4 cup semi-sweet chocolate chips, for pockets of melty chocolate.

Step-by-step Instructions

Preheat the oven to 350°F (177°C) and position the rack in the center. Line a 9×13-inch baking pan with parchment paper, leaving some overhang to lift out the bars easily.
In a medium bowl, whisk together the flour, cornstarch, baking soda, and salt until evenly combined. This ensures even leavening and a consistent texture.
In a large bowl, mix the melted and cooled butter with the brown sugar and granulated sugar until smooth and combined. Scrape the sides so no dry sugar remains.
Add the eggs and vanilla to the butter-sugar mixture, mixing until incorporated and glossy. Mixing just until combined keeps the bars tender.
Combine the wet and dry ingredients, stirring until just mixed. Do not overmix, or the bars can become tough.
Fold in the M&Ms and chocolate chips until evenly distributed. Reserve a few M&Ms to press on top if you want a decorative finish.
Spread the dough in the prepared pan and smooth it out into an even layer. If using reserved M&Ms, press them gently into the top for a colorful look.
Bake for 26 to 30 minutes or until the top is lightly browned and a toothpick inserted near the center comes out mostly clean with a few moist crumbs. Start checking at 26 minutes to avoid overbaking.
Cool in the pan for at least one hour, then use the parchment overhang to lift the slab out and cut it into squares. Cooling fully helps the bars set so they slice cleanly.

Tip: If you like extra melty pockets of chocolate, warm the pan slightly before serving so the chips soften again. For a treat variation, try a recipe-inspired idea from our cheesecake bar family of desserts.

Recipe Details

Prep Time: 15 minutes
Cook Time: 26 to 30 minutes
Total Time: about 1 hour 45 minutes, including at least 1 hour of cooling
Servings: about 24 squares
Calories: approximately 250 kcal per serving

Tips, Storage & Variations

Tips: Measure flour correctly by spooning it into the cup and leveling it off. Let the melted butter cool slightly so it does not cook the eggs when mixed. Press a few M&Ms on top before baking for a picture-perfect finish.
Storage: Store cooled bars in an airtight container at room temperature for up to 3 days. Separate layers with parchment to prevent sticking.
Freezing: Wrap individual squares tightly in plastic wrap and place in a freezer-safe bag for up to 3 months. Thaw at room temperature before serving.
Flavor variations using only the existing ingredients:
- Increase the chocolate chips to 1 cup and reduce M&Ms to 1 cup for a more chocolate-forward bar.
- Use only mini M&Ms for more even candy distribution and smaller chocolate bursts.
- Press extra M&Ms on top before baking for a candy-topped version.

You might also enjoy a denser, gooier pan dessert such as our chocolate caramel dump cake for another easy crowd-pleaser.

Frequently Asked Questions

How do I prevent the M&Ms from bleeding color?
Use mini M&Ms or press some on top after baking. Avoid stirring too aggressively so the candy coating stays intact.
Can I use salted butter instead of unsalted?
Yes, reduce added salt slightly or omit it if you prefer, since salted butter adds sodium.
Will these bars be cakey or chewy?
They are tender and slightly chewy with a soft crumb thanks to the cornstarch and brown sugar.
Can I make these ahead of time for a party?
Yes, bake and cool completely, then store in an airtight container. Bring to room temperature before serving.
How do I know when the bars are done baking?
The top should be lightly browned and a toothpick inserted near the center should come out mostly clean with a few moist crumbs.

Conclusion

These M&M Chocolate Chip Bars are an easy, feel-good dessert that comes together quickly and pleases kids and adults alike. If you want another take on colorful cookie bars, see this EASY M&M Cookie Bars – I Heart Naptime for inspiration, or try a softer, chewier version with the Soft M&M Cookie Bars Recipe – Sally’s Baking Addiction. Please try the recipe, share photos, and tell friends how they turned out. Enjoy baking and sharing these sweet, chocolate-studded bars with people you love.

M&M Chocolate Chip Bars

Print Recipe

These M&M Chocolate Chip Bars are a joyful twist on a classic cookie bar, featuring a buttery, tender crumb studded with colorful M&Ms and melty chocolate chips.

Author: hannah-reed
Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 105 minutes
Yield: 24 squares 1x
Category: Dessert
Method: Baking
Cuisine: American
Diet: Vegetarian

Ingredients

Scale

2 and 3/4 cups all-purpose flour
1 and 1/2 teaspoons cornstarch
1 teaspoon baking soda
1/2 teaspoon salt
1 cup unsalted butter, melted and cooled
1 cup packed light or dark brown sugar
1/2 cup granulated sugar
2 large eggs, at room temperature
2 teaspoons pure vanilla extract
1 and 1/4 cups mini or regular-size M&Ms
3/4 cup semi-sweet chocolate chips

Instructions

Preheat the oven to 350°F (177°C) and position the rack in the center. Line a 9×13-inch baking pan with parchment paper.
Whisk together the flour, cornstarch, baking soda, and salt in a medium bowl.
Mix the melted and cooled butter with the brown sugar and granulated sugar until smooth in a large bowl.
Add the eggs and vanilla to the butter-sugar mixture and mix until incorporated.
Combine the wet and dry ingredients, stirring until just mixed.
Fold in the M&Ms and chocolate chips until evenly distributed.
Spread the dough in the prepared pan and smooth it out.
Bake for 26 to 30 minutes or until the top is lightly browned and a toothpick comes out mostly clean.
Cool in the pan for at least one hour, then lift out and cut into squares.